At the time of European encounter, the area was occupied by the indigenousMohican Indians. To the west of the river were the Mohawk and other four tribes of the Iroquois Confederacy, extending past what is now the border of New York state. The first known European exploration of Columbia County was in 1609, when Henry Hudson, an English explorer sailing for the Dutch, ventured up the Hudson River. An accident to his craft forced him to stop at what is now known as Columbia County, and search for food and supplies.[3] In 1612, the Dutch established trading posts and minor settlements, constructing New Amsterdam (today New York City) and Fort Orange (today Albany). Fort Orange became a center of the fur trade with the Mohawk people. Traders began to stop at midway points along the Hudson River, on their travels between New Amsterdam and Fort Orange. Small settlements arose along the river to supply the traders' ships.[3]

In 1649, Dutch colonists purchased land near Claverack and in 1667, more land was purchased.[4] As more Dutch arrived, the region slowly developed. In 1664, the English took over New Netherland and renamed it the Province of New York; they also renamed Fort Orange as Albany.[4]

In the late 17th century, Robert Livingston, a Scots immigrant by way of Rotterdam, built on his connections as Indian agent in the colony and purchased two large portions of land from the Native Americans. He gained much larger grants from the provincial government, for a total of 160,240 acres. He was made lord of the manor by the Crown, with all its perquisites, and started to develop the property with tenant farmers. In 1710, he sold 6,000 acres of his property to Queen Anne of England for use as work camps and resettlement of Palatine German refugees. The Crown had supported their passage to New York, and they were to pay off the costs as indentured labor.[5] Some 1200 Palatine Germans were brought to Livingston Manor (now known as Germantown). New York's Governor Hunter had also helped with these arrangements: the workers were to manufacture naval stores (e.g., pitch, resin, and turpentine) from the pine trees in the Catskill Mountains.

They were promised land for resettlement after completing their terms of indenture.[4] They were refugees from years of religious fighting along the border with France, as well as crop failures from a severe winter.[5] Work camps were established on both sides of the Hudson River. The Germans quickly established Protestant churches at the heart of their community, which recorded their weddings, births and deaths, among the first vital records kept in the colony.[5]

After many years, some of the colonists were granted land in the frontier of the central Mohawk Valley west of present-day Little Falls in the 100 lots of the Burnetsfield Patent; in the Schoharie Valley, and other areas, such as Palatine Bridge along the Mohawk River west of Schenectady. They were buffer communities between the British settlements and the Iroquois and French (the latter located mostly in Canada.)

Columbia County was formed in 1786 after the American Revolutionary War from portions of Albany County, once a vast area until new communities were developed and jurisdictions were organized. In 1799, the southern boundary of Columbia County was moved southward to include that portion of Livingston Manor located in Dutchess County.

Voters in Columbia County since the mid-19th century have mostly elected Republicans to office. But from 1996 - 2007, new voter registrations by Democrats have outpaced those by Republicans by a margin of 4 to 1.[6] This substantial shift in party affiliation is due in large part to an influx of people from New York City who now live either full or part-time in Columbia County.

Organizations such as "Vote Columbia" have led efforts to have New York City residents, who live in a heavily Democrat-controlled area, re-register to vote in their part-time residence of Columbia County, thus influencing the demographic of a lightly populated area that is home to an increasing number of people in weekend houses or retirement.[7] Local residents have expressed dismay that voters who stay in the county only on the weekends are influencing its politics and decisions over development, schools and other issues.[7]

The rise in the number of Democrats has resulted in a virtual tie among the number of Democrats, Republicans and non-affiliated voters in Columbia County.[citation needed] In the 2007 election cycle, Democrats came within two seats of taking control of the county Board of Supervisors. In the 2009 local elections, the Republicans increased their majority on the Board of Supervisors through the defeat of longtime Kinderhook Supervisor Doug McGivney. As Supervisor of the largest Town in the County, McGivney had the largest weighted vote on the Board of Supervisors.[citation needed] The Board of Supervisors is now led by Supervisor Pat Grattan (R-Kinderhook).

The highest point is on the Massachusetts state line near the summit of Alander Mountain, at approximately 2,110 feet (643 m) above sea level, in the town of Copake. The lowest point is at or near sea level along the Hudson.

Columbia County is accessible by two limited-access highways. The Taconic State Parkway, which is not accessible to trucks or commercial traffic, runs through the center of the county from south to north, ending at an interchange with Interstate 90 and connecting the county with points south. Columbia County is the final New York county located along eastbound Interstate 90 (and the first county along westbound I-90), which passes through the towns of Chatham and Canaan as the Berkshire Connector portion of the New York Thruway. I-90 has two exits within the county; for the southbound Taconic State Parkway in Chatham, and for NYS Route 22 in Canaan.

There were 24,796 households out of which 29.90% had children under the age of 18 living with them, 52.20% were married couples living together, 10.30% had a female householder with no husband present, and 33.10% were non-families. 27.10% of all households were made up of individuals and 11.50% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 2.95.

In the county the population was spread out with 24.10% under the age of 18, 6.40% from 18 to 24, 26.90% from 25 to 44, 26.30% from 45 to 64, and 16.40% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 99.00 males. For every 100 females age 18 and over, there were 95.30 males.

The median income for a household in the county was $41,915, and the median income for a family was $49,357. Males had a median income of $34,702 versus $25,878 for females. The per capita income for the county was $22,265. About 6.40% of families and 9.00% of the population were below the poverty line, including 11.80% of those under age 18 and 6.80% of those age 65 or over.